code: def test_duplicate(self):
      rv = self.app.post(
          "/ensemble/",
          data=json.dumps({"ensemble_name": self.test_location}),
          content_type="application/json",
      )
  
      rv = self.app.post(
          "/ensemble/",
          data=json.dumps({"ensemble_name": self.test_location}),
          content_type="application/json",
      )
  
      assert rv.status_code == 400
  
file_path: xcessiv/xcessiv/tests/test_views.py
imports: from __future__ import absolute_import, print_function, division, unicode_literals
  import unittest
  import json
  import os
  from xcessiv import app, functions, models, constants
label_desc: Use image node_id 4 for calling the TestCreateNewEnsemble obj's underlying member method code with example usage: obj.test_duplicate() without return types